In stage lighting devices, one object is to obtain as much output lighting effect as possible from the light. The optical systems often produce large amounts of light. The projected light includes visible part but also includes large amount of heat therein.
FIG. 1 illustrates a prior art attempted solution to this problem. The light source 100 may produce a light output of 700 W or more output.
The light beam is coupled to an ultraviolet/infrared filter, which rejects the passage of at least one of IR or UV components therethrough. The output light 120 is cleansed, as much as possible, of non-visible light. This light may be further processed by light altering elements, e.g., the gobo 130.
It was found by the inventor, however, that the FIG. 1 system causes rejected energy to pass back to the lamp 100.